pack-bitmap-write: remove unused bitmap_reset() function

This function hasn't been used since 449fa5ee06 (pack-bitmap-write:
ignore BITMAP_FLAG_REUSE, 2020-12-08), which was a cleanup commit
intending to get rid of the code around the reusing of bitmaps.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

ewah/bitmap.c

@@ -216,11 +216,6 @@ int bitmap_is_subset(struct bitmap *self, struct bitmap *other)
 	return 0;
 }
 
-void bitmap_reset(struct bitmap *bitmap)
-{
-	memset(bitmap->words, 0x0, bitmap->word_alloc * sizeof(eword_t));
-}
-
 void bitmap_free(struct bitmap *bitmap)
 {
 	if (bitmap == NULL)

ewah/ewok.h

@@ -177,7 +177,6 @@ struct bitmap *bitmap_dup(const struct bitmap *src);
 void bitmap_set(struct bitmap *self, size_t pos);
 void bitmap_unset(struct bitmap *self, size_t pos);
 int bitmap_get(struct bitmap *self, size_t pos);
-void bitmap_reset(struct bitmap *self);
 void bitmap_free(struct bitmap *self);
 int bitmap_equals(struct bitmap *self, struct bitmap *other);
 int bitmap_is_subset(struct bitmap *self, struct bitmap *other);